The present invention relates to two-way or bi-directional pilot type electromagnetic flow valves and bi-directional piping that utilizes such bi-directional pilot type electromagnetic flow valves. In this specification, xe2x80x9ctwo-wayxe2x80x9d or xe2x80x9cbi-directionalxe2x80x9d is intended to mean a structure having ports A and B, in which a fluid may flow from port A to port B, or conversely, the fluid may flow from port B to port A.
A known pilot type electromagnetic flow valve is described in Japanese Utility Model Publication No. 59-83262 (1984) and is shown herein in FIG. 1. A body 1 includes a flow inlet port 2 and a flow outlet port 3 that are connected by a passage 4. A valve seat 5 is formed at the upper end of the passage 4. A cup-shaped main valve 6 reciprocates up and down within the body 1. A pilot space 7 is formed inside the main valve 6. A pilot hole 8 is defined at a bottom center of the main valve 6 and a ring shaped protrusion 9 surrounds the pilot hole 8 on the outside bottom surface of the main valve 6. The ring shaped protrusion 9 is free to contact or separate from the valve seat 5. A solenoid coil 10 is provided at the upper end of the body 1 and a plunger 11 and a spring 13 are provided inside the solenoid coil 10. A spherical pilot valve 12 is attached to the tip of the plunger 11. A narrow gap 14 is provided between the outer peripheral surface of the main value 6 and the inside surface of the body 1.
When the solenoid coil 10 is not energized, the pilot valve 12 closes the pilot hole 8 due to the biasing force of the spring 13. When the solenoid coil 10 is energized, the pilot valve 12 is pulled away from the pilot hole 8 due to the magnetic pulling or attracting force of the solenoid coil 10.
Normally, the fluid pressure at the flow inlet port 2 is greater than the fluid pressure at the flow outlet port 3. While the solenoid coil 10 is not energized and the pilot valve 12 closes the pilot hole 8, the pressure difference between the pilot space 7 and the flow outlet port 3, which works on the main valve 6, maintains the main valve 6 at the closed position. It is not required to energize the solenoid coil 12 to maintain the main valve 6 at the closed position. When the solenoid coil 10 is energized and the pilot valve 12 is pulled away from the pilot hole 8, fluid can communicate between the pilot space 7 and the flow outlet port 3, thereby eliminating the pressure difference between the pilot space 7 and the flow outlet port 3. In this condition, greater fluid pressure at the flow inlet port 2 than the pilot space 7 lifts the main valve 6 upwardly, and the ring shaped protrusion 9 will separate from the valve seat 5. Because the fluid pressure supplied to the flow inlet port 2 is greater than the fluid pressure at the flow outlet port 3, fluid will flow from the flow inlet port 2 toward the flow outlet port 3.
The required force for pulling away the pilot valve 12 from the pilot hole 8 by the solenoid coil 10 is much less than a force required for pulling away the main valve 6. A small solenoid coil 10 may be used for opening the pilot type electromagnetic valve that has the pilot valve 12, pilot hole 8 and pilot space 7. If the pilot valve 12, pilot hole 8 and pilot space 7 are not provided, and the main valve 6 is directly connected to the solenoid coil 10, a big solenoid coil 10 is required to pull away the main valve 6 from the valve seat 5, because the great pressure difference between the flow inlet port 2 and the flow outlet port 3 works on the main valve 6 to maintain the main valve 6 at the closed position.
When the main valve 6 should be closed again, the electric current to the solenoid coil 10 is stopped. As a result, the spring 13 causes the pilot valve 12 to contact and close the pilot hole 8. Thus, the high pressure fluid supplied from the flow inlet port 2 passes through the gap 14 into the pilot space 7, thereby pushing the main valve 6 downward as shown in FIG. 1. When the main valve 6 moves downward, the ring shaped protrusion 9 again comes into contact with the valve seat 5 and fluid communication between the flow inlet port 2 and flow outlet port 3 is stopped.
The cross sectional area of the main valve 6 is much bigger than the cross sectional area of the pilot valve 12 and the plunger 11. Therefore the force applied to the main valve 6 due to the pressure difference between the flow inlet port 2 and flow outlet port 3 is much higher than the force applied to the pilot valve 12 due to the pressure difference. If the pilot valve 12 is not provided, a relatively strong force would be required to move the main valve 6 upwardly against the large force due to the pressure difference between the flow inlet port 2 and flow outlet port 3, in order to open the main valve 6. Thus, if the pilot valve 12 is not provided, a solenoid coil 10 capable of generating a relatively strong pulling force is necessary to pull the main valve 6 upward.
However, the pilot valve 12 of the known pilot type electromagnetic flow valve can be easily opened by applying a small pulling force to the pilot valve 12, even if a large pressure difference exists between the flow inlet port 2 and flow outlet port 3. As a result, a relatively small solenoid coil 10 is sufficient to operate the known pilot type electromagnetic flow valve.
Consequently, the known pilot type electromagnetic flow valve, has the advantage of being able to use a small solenoid coil 10 to open the flow path, even when a large pressure difference exists between the flow inlet port 2 and the flow outlet port 3. In order to realize this advantage, the spring 13 must have a relatively small or weak biasing force.
In a typical piping system, the direction of the fluid flow is designed to flow in from the flow inlet port 2 and flow out from the flow outlet port 3 while passing though the pilot type electromagnetic flow valve in an opened state. Thus, the known pilot type electromagnetic flow valve can be utilized in typical piping systems, as long as the fluid pressure at flow inlet port 2 is greater than the flow outlet port 3.
However, if the fluid pressure at the flow outlet port 3 becomes higher than the fluid pressure at the flow inlet port 2, the known pilot type electromagnetic flow valve has little capability to reliably prevent fluid flow in the reverse direction. When relatively high pressure fluid is supplied to the flow outlet port 3, the main valve 6 will easily open, if the biasing force of the spring 13 is relatively small. In the known art, this reverse flow problem can be overcome by substantially increasing the biasing strength of the spring 13. If the spring 13 pushes the valves 6 and 12 downwardly with a greater force, the spring 13 will prevent high pressure fluid supplied to the flow outlet port 3 from opening the main valve 6. However, in this case, a relatively strong force will be required to pull away the pilot valve 12 against the strong biasing force of the spring 13 to open the pilot hole 8, and the advantage of pilot type electromagnetic flow valve will be lost.
Thus, in normal operation (i.e. a relatively high pressure fluid is supplied to the flow inlet port 2), a relatively strong electromagnetic force will be required to open the pilot valve 12 in order to overcome the increased biasing strength of spring 13. Consequently, in order to overcome the reverse flow problem, the advantage of using a pilot type electromagnetic valve will be eliminated, because it will be necessary to use a relatively large solenoid coil in order to supply a sufficient pulling force in order to open the flow path. Thus, the knowing pilot type electromagnetic valve is typically not used in two-way or bi-directional piping, because reverse flow can not be reliably prevented without losing the advantages of the pilot type electromagnetic valve.
Thus, the known pilot type electromagnetic valve is typically not used in two-way or bi-directional piping, because reverse flow can not be reliably prevented without losing the advantages of the pilot type electromagnetic valve. Instead, an electromagnetic flow valve without a pilot valve is typically used in two-way or bi-directional piping. As a result, a relatively strong spring force is utilized to maintain the valve in the closed position and a relatively strong electromagnetic force is required to open the valve. Thus, the size of the electromagnetic flow valve must be increased and a relatively large amount of energy is consumed in order to operate such a valve in a bi-directional piping system.
Therefore, it is accordingly, one object of the present teachings to overcome at least one problem of the known art. In one aspect of the present teachings, pilot type electromagnetic flow valves are taught that are capable of reliably preventing reverse flow in two-way or bi-directional piping. Such valves provide the advantage that a relatively small biasing force can be utilized to maintain the valve in the closed position and a relatively small electromagnetic force can be utilized to open the valve. Thus, a small solenoid can be utilized, thereby permitting a reduction in the size of the valve. Further, power consumption can be reduced, because the present teachings utilize the advantages of pilot type electromagnetic valves. Hereinafter, pilot type electromagnetic flow valves will sometimes be interchangeably referred to simply as xe2x80x9cpilot-assisted valves.xe2x80x9d
For example, in one embodiment of a two-way piping system described herein, two pilot-assisted valves are disposed between a flow inlet port and a flow outlet port in series and arranged in opposing operational directions. That is, the valve opening directions of the respective pilot-assisted valves are oppositely disposed along the fluid communication path between the two pilot-assisted valves. The particular order in which the pilot-assisted valves are disposed does not matter. However, as shown in FIG. 2 (A) and (B), it is preferable that normal valve opening directions of the pilot-assisted valves are oppositely disposed within the fluid path.
One embodiment of the present teachings is shown in FIG. 2 (A), in which a pilot-assisted valve 22 includes a solenoid coil 27 and a main valve 28 that moves toward the solenoid coil 27 when the solenoid coil 27 is energized, as shown in FIG. 2 (A). Solid line 28a shows the main valve 28 in the valve open position and broken line 28b shows the main valve 28 in the valve closed position. A spring (not shown in FIG. 2(A)) normally biases the main valve 28 towards the valve closed position. The pilot valve is also omitted from FIG. 2 (A) for the purpose of clarity. The pilot-assisted valves 24, 32, and 34 also may preferably have the same structure as the pilot-assisted valve 22, although naturally various designs are possible according to the present teachings. Ports 20, 26, 30, and 36 are also provided to supply and discharge fluid through the two representative examples of two-way or bi-directional piping.
In the piping shown in FIG. 2 (A), the pilot-assisted valves 22 and 24 are disposed in the opposite valve flow directions. That is, the relationship of the open and closed positions of the main valves of the pilot-assisted valves 22 and 24 are disposed in an opposite relationship. In other words, the valve opening directions of the pilot-assisted valves 22 and 24 are oppositely disposed within the fluid communication path. A first port 22a of the first pilot-assisted valve 22 directly communicates with a second port 24b of the second pilot-assisted valve 24 via flow path 23.
In the two-way or bi-directional piping shown in FIG. 2 (13), the pilot-assisted valves 32 and 34 are also disposed in the opposite valve opening directions. More specifically, the first port 32a of the first pilot-assisted valve 32 is connected to the flow port 30, and the second port 34a of the second pilot-assisted valve 34 is connected to the fuel outlet port 36. As a result, the main valve of the first pilot-assisted valve 32 opens towards the left in FIG. 2 (B) and the main valve of the second pilot-assisted valve 34 opens towards the right in FIG. 2 (B).
FIGS. 2 (A) and (B) show two representative embodiments in which pilot type electromagnetic flow valves are disposed in an opposing relationship. In both cases, the arrangement of the flow ports 20, 30 and the first pilot type electromagnetic flow valves 22, 32 is same as the arrangement of the flow ports 26, 36 and the second pilot type electromagnetic flow valves 24, 34. The flow ports 20, 30 may be interchangeably used as the flow inlet port or outlet port. Likewise, the flow ports 26, 36 may be interchangeably used as the flow outlet port or inlet port.
In the configuration shown in FIG. 2 (A), the fluid pressure supplied to port 20 is usually higher than the fluid pressure at port 26. Therefore; when the pilot-assisted valves 22, 24 are open, fluid will flow from port 20 to port 26. Thus, for purpose of discussion, port 20 will be referred to as flow inlet port 20 and the opposing port will be referred to as flow outlet port 26. However, as will be clearly appreciated, because the present valves and piping are bi-directional in nature, port 20 could also be utilized as the flow outlet port and port 26 could be utilized as the flow inlet port.
If a relatively small magnetic pulling force is applied to the pilot valve of the pilot-assisted valve 22 in order to permit fluids to be communicated through the structure shown in FIG. 2(A), the pilot type electromagnetic flow valve 24 will permit the fluid to flow from the flow inlet port 20 toward the flow outlet port 26. When the magnetic pulling force applied to the pilot type electromagnetic flow valve 22 is stopped, the pilot type electromagnetic flow valve 22 will close. At this time, the relatively high pressure fluid supplied to the flow inlet port 20 forces the pilot type electromagnetic flow valve 22 to remain in the closed state.
On the other hand, when the fluid pressure supplied to the flow outlet port 26 is greater than the fluid pressure at flow inlet port 20, the pilot type electromagnetic flow valve 24 can act as anti-reverse flow valve, thereby stopping or preventing reverse flow from fuel outlet port 26 to fuel inlet port 20. By disposing two pilot type electromagnetic flow valves in series and in opposing operational directions, reverse flow can be reliably stopped or prevented. Further, when a relatively high pressure fluid is supplied to the flow outlet port 26, the pilot type electromagnetic flow valve 24 can still be opened with a small magnetic pulling or attracting force. If pilot type electromagnetic flow valve 24 is opened, fluid will flow in the reverse direction from the flow outlet port 26 toward the flow inlet port 20.
Further, when a relatively high pressure fluid is supplied the flow inlet port 20, the fluid path will remain closed due to the pilot type electromagnetic flow valve 22, unless the solenoid coil 27 of the pilot type electromagnetic flow valve 22 is energized. That is, by passing electric current through the solenoid coil 27, the pilot type electromagnetic flow valve 22 will be opened. When high pressure fluid is applied at the flow outlet port 26, the fluid path will remain closed due to the pilot type electromagnetic flow valve 24, unless the solenoid coil 27 of the pilot type electromagnetic flow valve 24 is energized. That is, by passing electric current through the solenoid coil 27, the pilot type electromagnetic flow valve 24 will be opened. According to this piping arrangement, the flow inlet port 20 and the flow outlet port 26 can communicate fluids only when so desired, and unintentional communication of fluids can be prevented.
When a relatively high pressure fluid is supplied the flow inlet port 20, the fluid path will remain closed due to the valve 22 unless the solenoid coil 27 of the valve 22 is energized. The fluid path will open by energizing the solenoid coil 27 of the valve 22. It is not required to energize the valve 24 to open the fluid path.
When a relatively high pressure fluid is supplied the flow outlet port 26, the fluid path will remain closed due to the valve 24 unless the solenoid coil 27 of the valve 24 is energized. The fluid path will open by energizing the solenoid coil 27 of the valve 24. It is not required to energize the valve 22 to open the fluid path.
Thus, a two-way piping system is provided that is capable of switching between the states of open communication and closed communication as desired by the pilot type electromagnetic flow valves.
Referring to the configuration shown in FIG. 2 (B), a relatively high pressure fluid may be supplied to port 30, which will be referred to as flow inlet port 30 for the purposes of discussion. Further, the port 36 that opposes flow inlet port 30 will be referred to as the flow outlet port 36. Similar to the embodiment shown in FIG. 2 (A), the orientation of ports 30 and 36 can be freely changed to refer to these ports as flow outlet port 30 and flow inlet port 36.
In the embodiment shown in FIG. 2 (B), when the fluid pressure at the flow inlet port 30 is greater than the fluid pressure at the flow outlet port 36 and the pilot type electromagnetic flow valve 34 is opened by applying a small magnetic pulling force, the pilot type electromagnetic flow valve 32 will permit fluid to flow from the flow inlet port 30 toward the flow outlet port 36. That is, the valve 32 is not capable of stopping flow from the flow inlet port 30 to the flow outlet port 36. When the fluid pressure at the flow inlet port 30 is greater than the fluid pressure at the flow outlet port 36 and the valve 34 is not energized, the valve 34 stops the flow from the flow inlet port 30 toward the flow outlet port 36 even if the valve 32 is not capable of stopping flow from the flow inlet port 30 to flow outlet port 36.
If the fluid pressure at the Bow outlet port 36 is greater than the fluid pressure at the flow inlet port 30 and the pilot type electromagnetic flow valve 32 is opened by applying a small magnetic pulling force, the pilot type electromagnetic flow valve 34 will permit fluid to flow from the flow outlet port 36 toward the flow inlet port 36. That is, the valve 34 is not capable of stopping flow from the flow outlet port 36 to the flow inlet port 30. When the fluid pressure at the flow outlet port 36 is greater than the fluid pressure at the flow inlet port 30 and the valve 32 is not energized, the valve 32 stops the flow from the flow outlet port 36 toward the flow inlet port 30 even if the valve 34 is not capable of stopping flow from the flow outlet port 36 to flow inlet port 30.
Thus, the piping arrangement shown in FIG. 2 (B) also provides a two-way piping system that is capable of switching between open and closed states as desired by the pilot type electromagnetic flow valves.
The two examples of two-way piping shown in FIG. 2 (A) and (B) are believed to be based upon a novel concept. In the known art, a single electromagnetic valve is used in two-way piping. The electromagnetic valve used in two-way piping is biased closed using a relatively large spring and the valve is opened using a relatively strong electromagnetic force. However, the piping arrangements shown in FIG. 2 (A) and (B) can utilize the advantages of pilot type electromagnetic flow valves. Thus, the pilot-assisted electromagnetic valve can be opened using a relatively small solenoid coil while still reliably preventing unintended or undesired reverse flow. In addition, the two-way piping can easily switch between the states of preventing reverse flow and permitting reverse flow. Moreover, the advantages of the pilot type electromagnetic flow valve can be realized in the present teachings, because a small solenoid coil can be utilized to switch the flow states.
Thus, in one embodiment of the present teachings, a two-way pilot type electromagnetic flow valve includes two pilot type electromagnetic flow valves connected in series and arranged in opposing valve opening directions. The two pilot type electromagnetic flow valves may preferably be disposed within a common body. Such a two-way pilot type electromagnetic flow valve may utilize a relatively small solenoid coil to open the valve and prevent reverse flow in addition to switching to permit reverse flow.
Although the movable valves of the two pilot type electromagnetic flow valves are preferably arranged in a straight line, other arrangements can be utilized. For example, if a straight-line is utilized, the two-way pilot type electromagnetic flow valves can be made narrow. In the alternative, the movable valves of two pilot type electromagnetic flow valves can be arranged in parallel, thereby realizing a shorter two-way pilot type electromagnetic flow valve.
In addition or in the alternative, the two movable valves may preferably share a common solenoid coil, thereby permitting the two movable valves to be moved (biased) using a single solenoid coil. Therefore, two movable valves can be simultaneously moved to open or close the valves and the number of parts can be minimized.
However, it is also possible to provide a solenoid coil for each of the two movable values, thereby simplifying the design and production of a two-way pilot type electromagnetic flow valve. If each of the two movable valves has its own solenoid coil, electric current can be passed to either one of the two solenoid coils in order to open the flow path. The pilot type electromagnetic flow valve can be switched easily to an opened state when a relatively high pressure fluid is applied to the flow outlet port. Thus, this method can be utilized to energize the solenoid coil and open the valve. In other words, instead of passing electric current to both of the two solenoid coils in order to open the two pilot type electromagnetic flow valves, one of the, pilot type electromagnetic flow valves can be opened by the fluid pressure differential. Thus, power consumption can be reduced if only one solenoid coil is energized during operation.
These aspects and features may be utilized singularly or in combination in order to make improved two-way pilot type electromagnetic flow valves. In addition, other objects, features and advantages of the present teachings will be readily understood after reading the following detailed description together with the accompanying drawings and the claims. Of course, the additional features and aspects disclosed herein also may be utilized singularly or in combination with the above-described aspects and features.